Kiln cars are well-known in the art and have been described in some detail in countless prior publications and patents. For example, see U.S. Pat. Nos. 1,739,176, 1,846,614, 1,908,186 and 3,094,759. The cars typically are used to transport ceramic ware through long kilns for the purpose of firing the ware, either for bisque or glost firing, at elevated temperatures, usually well in excess of 1500.degree. F. Usually, the cars have conventional, flanged running gear for track transport, and are slowly pushed through a long cavernous tunnel kiln in end-to-end, abutted relationship. The chassis of the cars is normally of heavy gauge, welded sheet steel, and to protect that steel, running gear, etc., and to minimize heat loss from the kiln, the cars have traditionally been topped with any number of ceramic refractory layers. See the U.S. Patents referred to above.
However, with the premium currently placed on energy conservation, it has been found that the massive, solid refractory covers and supports used heretofore for protecting the top of the kiln car and for supporting ceramic ware to be fired thereon, are exceedingly wasteful of energy in two major respects.
First, in order to stabilize the firing cycle within the kiln, the massive refractory structures used heretofore literally had to be heated to essentially the same temperature as the temperature at which the ware it carried was being fired. Secondly, because of the solid, dense structure of kiln car tops used heretofore, those tops became heat conductors during the firing cycle through the tunnel kiln, and literally transmitted the heat away from where it was needed most, i.e. from the upper levels where the supported ware to be fired was situated, down through the massive supporting, solid refractory to the bottom, metal chassis and running gear of the kiln car.
The instant invention essentially eliminates extensive heat loss through the kiln car top by providing a highly insulating cover for the kiln car, which transmits relatively little heat away from the kiln atmosphere and furthermore, because of its relatively light-weight structure, does not rob the kiln of any appreciable amount of heat, thereby enhancing heat stabilization within the kiln. That is, because the kiln car top of this invention does not function as a heat sink for robbing the kiln interior of heat, the stability of the ambient temperature within the kiln is materially improved, in that cold spots are all but removed in the hot zone, and temperature gradients from top to bottom, and from side to side, are materially reduced.
The means for achieving the insulated kiln car top of this invention, stated in simplest terms, is the utilization of a series of modular, inverted, cup-shaped refractory members in a row along two opposed edges of the kiln car supporting surface. When the cars are in abutted, operational, tunnel-kiln relationship, these members essentially form a continuous pair of side rails, along a pair of opposed linear edges, of a tunnel kiln car train. Being of hollow, relatively thin, refractory material, the modular members aforesaid may be filled with conventional, refractory insulating material. The space between the two insulating, retaining walls or rails aforesaid, may then be loosely, though optimally, packed with conventional refractory, insulating fiber up to a height roughly coincident with the tops of the inverted, cup-shaped members aforesaid, to thereby provide an insulating kiln car top which serves to prevent any substantial heat loss from the kiln ambience down through to the kiln car chassis. By "optimally" packed fibrous insulation, is meant that it is packed in such a way as to provide maximum heat insulation; that is, too densely, or too loosely, packed insulation reduces its insulating value.
By "modular" is meant a certain degree of interchangeability or flexibility, whereby, for example, end member "A" of FIG. 4 may be used on the rectangular surface of any kiln car, regardless of its length (or width). The same applies to intermediate modules "B" of FIG. 4. Then, for larger, or shorter, kiln cars, only center module "C" would have to be specially tooled for a given size car, for a particular kiln. It being well known that cars designed for a given kiln are of uniform dimensions.
Although not essential to the practice of the instant invention, and as will be disclosed in more detail hereinafter, a relatively thin, light-weight, refractory post and plate arrangement may be utilized in conjunction with the instant invention, whereby the posts may extend down to, or through, the insulating modular members to the kiln car supporting surface, which ultimately carries the load of the ware in spaced-above position with respect to the insulated kiln car top.
As will be readily apparent, the instant invention is equally applicable to either tunnel kiln, or shuttle kiln, cars with but minor modification. That is, for tunnel kiln application, since the cars are inside the kiln in a relatively long train, in end-to-end snugly abutting relationship with respect to each other, the modular members of this invention are placed along each of a pair of opposed edges of the car, parallel to its axis of travel. However, this invention also contemplates that the modular members could also be arranged along the front and back edges of the car, in a second pair of opposed rows, normal to the axis of travel, if desired. Thus, a tunnel kiln car may optionally have said modular members disposed around the entire periphery of its top, or just along the two edges parallel to its line of travel.
If the kiln car is to be used in a shuttle kiln, wherein only one or two kiln cars will be in the kiln at a time, on a periodic basis, then the modular members of this invention would normally be disposed in two sets of opposed rows, essentially conforming to the kiln car top periphery, in order to provide complete heat protection.
The essence of this invention then, resides in at least two rows of the modular members of this invention, disposed across from each other, along a pair of opposed edges of a kiln car top. The space between the two rows of modular members will have at least a layer of refractory insulation on the kiln car top, and the modular members may optionally contain refractory insulation material.